User Guide

Technical Documentation
NHD–4
System Module
P.A.M.S
Page 4–25
Original 11/97
For operation with the LNA ”on”, RF is routed into the first switch, N702 at
pin 5. It exits at pin 7 and enters the LNA through L22. After amplification
the receive signal leaves the LNA through C98 and enters the second RF
switch, N701, at pin 7. The signal exits the second switch through pin 5
and proceeds into the UHF RX SAW (Z1) through C771. Switching
control is accomplished at pins 8 and 1 for both switches. For operation
with the LNA (V12) ”on”, or CDMA Hi–Gain, the RX_CAL line at R783/R6
should be logic ”high” at approximately 2.80 V. The SWAGC line at R830
should be logic level ”low”, approximately 0.00 V. The VCONT2 pins (pin
1) of N701 and N702 should be approximately 3.80 V. The VCONT1 pins
(pin 8) should be approximately 0.0 V.
For operation with the LNA ”off”, RF is routed into the first switch, N702 at
pin 5. It exits at pin 2 and enters a resistive matching network through
C787, consisting of R827, R834, and R828. It leaves this network through
C804 and enters the second RF switch, N701, at pin 2. The signal exits
the second switch through pin 5 and proceeds into the UHF RX SAW (Z1)
through C771. Switching control is accomplished at pins 8 and 1 for both
switches. For operation with the LNA ”off”, or CDMA Lo–Gain, the
RX_CAL line at R783/R6 should be logic ”low” at approximately 0.00 V.
The SWAGC line at R830 should be logic level ”high”, approximately 3.00
V. The VCONT2 pins (pin 1) of N701 and N702 should be approximately
0.00 V. The VCONT1 pins (pin 8) should be approximately 2.90 V.
The following truth table details the states of the switches and the LNA
verse the modes of the phone. This table is also found on the RX
schematic.
State RXCAL LNA VCONT1 SWAGC VCONT2
AMPS 1 ON 0 0 1
CDMA Hi–Gain 1 ON 0 0 1
CDMA Lo–Gain 0 OFF 1 1 0
RXCAL 0 OFF 0 0 1
LNA (V12) and RX SAW Filter (N701)
Current to source this device originates from the V11 network. C98
delivers the amplified UHF RX signal to the second RF switch N701, pin 7.
The output of N701 (pin 5) routes the signal to the UHF RX SAW Filter
(Z1). The UHF signal leaves the SAW at pin 5 and enters the mixer
through C41.